package com.lkx.demo.springcloud.provider.hystrix;

import com.lkx.demo.springcloud.provider.utils.ThreadLocalUtils;
import com.netflix.hystrix.HystrixThreadPoolKey;
import com.netflix.hystrix.strategy.HystrixPlugins;
import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariable;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariableLifecycle;
import com.netflix.hystrix.strategy.eventnotifier.HystrixEventNotifier;
import com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook;
import com.netflix.hystrix.strategy.metrics.HystrixMetricsPublisher;
import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;
import com.netflix.hystrix.strategy.properties.HystrixProperty;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * 构建一个上下文装饰器
 *
 * @author : liukx
 * @create : 2018/7/10 13:56
 * @email : liukx@elab-plus.com
 */
public class FeignHystrixConcurrencyStrategy extends HystrixConcurrencyStrategy {

    private static final Logger log = LoggerFactory.getLogger(FeignHystrixConcurrencyStrategy.class);
    private HystrixConcurrencyStrategy delegate;

    public FeignHystrixConcurrencyStrategy() {
        try {
            this.delegate = HystrixPlugins.getInstance().getConcurrencyStrategy();
            if (this.delegate instanceof FeignHystrixConcurrencyStrategy) {
                // Welcome to singleton hell...
                return;
            }
            HystrixCommandExecutionHook commandExecutionHook = HystrixPlugins.getInstance().getCommandExecutionHook();
            HystrixEventNotifier eventNotifier = HystrixPlugins.getInstance().getEventNotifier();
            HystrixMetricsPublisher metricsPublisher = HystrixPlugins.getInstance().getMetricsPublisher();
            HystrixPropertiesStrategy propertiesStrategy = HystrixPlugins.getInstance().getPropertiesStrategy();
            this.logCurrentStateOfHystrixPlugins(eventNotifier, metricsPublisher, propertiesStrategy);
            HystrixPlugins.reset();
            HystrixPlugins.getInstance().registerConcurrencyStrategy(this);
            HystrixPlugins.getInstance().registerCommandExecutionHook(new MyHystrixHooK());
            HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);
            HystrixPlugins.getInstance().registerMetricsPublisher(metricsPublisher);
            HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);
        } catch (Exception e) {
            log.error("Failed to register Sleuth Hystrix Concurrency Strategy", e);
        }
    }

    private void logCurrentStateOfHystrixPlugins(HystrixEventNotifier eventNotifier,
        HystrixMetricsPublisher metricsPublisher, HystrixPropertiesStrategy propertiesStrategy) {
        if (log.isDebugEnabled()) {
            log.debug("Current Hystrix plugins configuration is [" + "concurrencyStrategy [" + this.delegate + "],"
                + "eventNotifier [" + eventNotifier + "]," + "metricPublisher [" + metricsPublisher + "],"
                + "propertiesStrategy [" + propertiesStrategy + "]," + "]");
            log.debug("Registering Sleuth Hystrix Concurrency Strategy.");
        }
    }

    /**
     * 将当前线程参数传递到要调用的方法中去
     *
     * @param callable
     * @param <T>
     * @return
     */
    @Override
    public <T> Callable<T> wrapCallable(Callable<T> callable) {
        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
        String body = ThreadLocalUtils.get();
        log.info("构建上下文 : " + body);
        return new WrappedCallable<>(callable, requestAttributes, body);
    }

    @Override
    public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey, HystrixProperty<Integer> corePoolSize,
        HystrixProperty<Integer> maximumPoolSize, HystrixProperty<Integer> keepAliveTime, TimeUnit unit,
        BlockingQueue<Runnable> workQueue) {
        return this.delegate
            .getThreadPool(threadPoolKey, corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
    }

    //    @Override
    //    public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey,
    //                                            HystrixThreadPoolProperties threadPoolProperties) {
    //        return this.delegate.getThreadPool(threadPoolKey, threadPoolProperties);
    //    }

    @Override
    public BlockingQueue<Runnable> getBlockingQueue(int maxQueueSize) {
        return this.delegate.getBlockingQueue(maxQueueSize);
    }

    @Override
    public <T> HystrixRequestVariable<T> getRequestVariable(HystrixRequestVariableLifecycle<T> rv) {
        return this.delegate.getRequestVariable(rv);
    }

    static class WrappedCallable<T> implements Callable<T> {
        private final Callable<T> target;
        private final RequestAttributes requestAttributes;
        private String body;

        public WrappedCallable(Callable<T> target, RequestAttributes requestAttributes, String body) {
            this.target = target;
            this.requestAttributes = requestAttributes;
            this.body = body;
        }

        @Override
        public T call() throws Exception {
            try {
                ThreadLocalUtils.set(body);
                RequestContextHolder.setRequestAttributes(requestAttributes);
                T call = target.call();
                return call;
            } finally {
                RequestContextHolder.resetRequestAttributes();
            }
        }
    }
}